Electronic piano tuning



Jan. 16, 1951 c. ANDERSEN ELECTRONIC PIANO TUNING Filed Aug. 7, 1946 Patented Jan. 16, 1951 UNITED STATES PIA-TENT" OFFICE Clifford Andersen, be Kalb, I ll., assignorto The Rudolph Wurlitzer Company, De Kalb, Ill.

Application August 7, 1946, Serial No. 688,897

a 4 Claims.

This. invention. relates to piano tuning, and particularly to an electrical pick up mechanism inan electronic circuit such as to amplify the sound waves developed from a selected piano stringover and above those of its associated unison of strings.

wherein piano strings are arranged in a unison of two or three strings for each note, it has been customary in tuning each string of the unison to dampen out the other strings by applying thereto rubber wedges, felt, or the like; This is necessar in order that the sound vibrations of the string being tuned'will not be interfered with by those of its associated strings.

J- It istheobject of this invention to eliminate the necessity of dampening out the associated strings by. amplifying the sound waves of the strin being tuned to distinguish it therefrom. This is accomplished by conveniently applying to such string being tuned a pick up mechanism for electrically transmitting the vibrations thereof to an audio amplifying circuit for sound amplification.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. 1 is a perspective view of the pick up mechanism.

Fig. 2 is a plan iew of the pick up mechanism with its housing shown in section.

Fig. 3 is the same. as Fig. 1 showing a side elevation thereof.

Fig. 4 is the same as Fig. 3 showing a modified form of pick up-mechanism.

In the drawings there is shown an electronic piano tuning device comprising an elongated .metal vibration transmitting element herein i1- lustrated as a rigid bar l0, to one end of which there is rigidl connected a spring clip H for conveniently contacting one of the unison of piano strings l2.

The vibration bar is rigidly connected at its other end to the electrical vibration transmitting pick up mechanism l3 such as the usual commercial phonograph pick up, well known in the art. In place of the usual pick up needle or stylus, the pick up I3 is rigidly connected with that end of the bar In opposed to the strin engaging clip H by the screw l4. Thus the screw 14 is inserted in the pick up I3 in the manner of a phonograph needle but is so formed as to be firmly fixed to the end of the bar l0. As herein shown it is threaded to be screwed therein. The pick up 13 is electrically connected through a cable I to anelectronic amplifier a z V I6, and frequency comparing and measuring unit H. The pickup I3 is preferably encased for handling within the housing l8 containing a felt wrapping or packing l9.

The frequency comparing and measuring unit H may be of various known types, one type comprising a cathode ray, tube with one set of defiection plates connected to the pick up through theaudio amplifier l6, and the. other set. of deflection plates to any well known and suit.- able audio frequency standard, not shown herein. The latter deflectionplates may be fed byv a controlled saw tooth wave oscillator to indicate flat or sharp as well a resonance. Another well known type of frequency comparing and meas- .uring unit is that known as the ,Stroboscope manufactured by C. G. Con-n, Ltd.,. of Elkhart, Indiana. By the use of this invention there is developed a higher signal to noise ratio resulting in a much better and clearer image seen on the frequency and measuring unit [1. The invention also eliminates the use ofrubber wedges and felts such as are necessary when using the usual microphone pick up. fl

7 In tuningfthe unison of stringsflshown herein as comprisin three piano strings, the clip II is engaged over the particular string to be selectively tuned. The string is contacted preferably betweenthe upper bearing-Iand the pressure bar, since if it is engaged fat the striking point the pitch thereof may be s'l htly changed. The unison of strings is then struck by the action hammer and although the other strings of the unison may be sounded as usual there will be sufficient amplification of th elected string being tuned transmitted throu and electroniccircuit to distinguish its frequency from that of the other strings of its unison.

In the modified form of the electronic tuning device the vibration bar H0 is connected to the electric pick up mechanism H3 through a small diameter rod H4 which is rigidly set in the bar to extend upwardly therefrom and be clamped in the pick up by the usual clamp screw 5. The opposite end of the pick up may be removably secured to and supported upon the end of the bar I It) by an anchor pin I I6. Preferably the pick up and the portion of the bar to which it is anchored is wrapped in felt and encased by a housing as above described.

Whereas the vibration bars to and Ill) have been shown herein as of varying lengths they may also be formed to any desired curvature or bent at any angle for convenient application to the piano string. Similarly, a flexible steel cable upon manual vibration thereof comprising; a.

mechanical vibration transmitting element, the receiving end of which is adapted. to be selectively placed in direct contact with a selected string to be tuned, an audio amplifying; circuit, and an electrical vibration transmitting pick up mechanism connected at one end thereof to the other end of said vibration transmitting element and -havinglits output end connected in said circuit for electrically transmitting mechanical vibra- .t'i'ons of the selected string to said audio amplifying circuit.

2; An electronic device for tuning piano strings upon manual vibration thereof comprising a mechanical vibration transmitting element, a spring contact clip secured to the vibration receiving end of said element for connecting it indirect contact with a selected string to be tuned, an audio amplifying circuit, a frequency comparing and measuring unit connected therewith and an electrical vibration transmitting pick up mechanism having a vibrating member rigidly connected with the other end of said'vibration transmitting element to mechanically transmit vibration from the manually vibrated string to said mechanism, said pick up mechanism having its output end electrically connected in said amplitying circuit. I

3. An electronic device for tuning piano strings upon manual vibration thereof comprising a mechanical vibration transmitting element, the receiving end of which is adapted to be selectively placed in direct contact with the selected string to be tuned, an audio amplifying circuit, a frequency comparing and measuring unit connected with the output end of said circuit, and an electrical vibration transmitting pickup mechanism connected at its in-put end to the other end of said mechanical vibration transmitting element and having its output end connected to the input end of said circuit for electrically transmitting vibrations of the selected string into said circuit for frequency measurement and comparison.

4. Themethcd of tuning a selected one of a unison of piano strings, consisting in selectively and directly engaging the selected string with an electronic pick up device for receiving mechanical vibrations therefrom, simultaneously striking all strings of the unison, and electrically amplifying the transmitted mechanical vibrations of the selected string of the unison for electronic frequency comparison: and measurement thereof.

CLIFFORD ANDERSEN;

REF ERENCES' CITED- The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,516,947 Beindorf Nov. 25,, 1924 1,669,170 Nicolson May 8, 192.8 1,896,683 Clarkv c Feb. 7, 1933 1,915,858. Mi'essner 1 June: 27, 1933 1,988,564 Nernst, Jan. 22, 1.935 

